With the development of the information communication technology, traditional analog television is replaced by Digital Television (DTV) and Internet Protocol Television or Interactive Personal Television (IPTV). Compared with traditional television, IPTV and DTV can provide various VOD services for flexible use.
Currently, a VOD service system is composed of a VOD server, an Electronic Program Guide (EPG) system, a Middle Ware (MW), and a Set-Top Box (STB) serving as a terminal. The VOD server is responsible for providing the program contents corresponding to various VOD service modes; the EPG system demonstrates the program contents and relevant services; the STB updates the EPG in the EPG system and provides the EPG for the user, and sends requests for using various VOD services as instructed by the user; the MW provides a service management and integration platform so that multiple “capability” components such as VOD server, EPG authentication server, and authorization and encryption system work on a unified platform.
A VOD service system in the prior art provides the following VOD services:
Time-Shifted Television (TSTV) or Pause Live Television (PLTV): This service allows the user to play back a live television program in a time window of a specific length; in the process of watching a live television program, the user may play back the program through a fast rewind key; TSTV imposes a specific time limit, called “time window”, on playing back. Generally, the operator sets the time window to 0.5-1 hour. When the program is played back to the start time of the window, no further rewinding is allowed and the normal play resumes. If the program is played in fast forward mode to the end of the window, the current channel is closed automatically, and the live channel is activated.
True Video on Demand (TVOD): This service allows the user to watch a program played in a past time segment; the operator generally records the programs played on a channel selectively, or records the whole channel according to the play time segment and provides the programs in a list for the user; the user may demand a specific program or the programs in a specific time segment as required. The recorded contents are generally retained for 1 day to 1 month.
Network Personal Video Recorder (nPVR): This service allows the user to reserve recording of a future program and watch the recorded program at any time in the future; the operator may define certain channels for providing nPVR services and display the future EPG of such channels to the user, and the user may select a future program to be recorded; when it is time to live cast the program, the VOD server starts recording and saving the media file; the user may demand and watch the programs recorded by the operator anytime within the maximum retention period specified by the operator, and the watching process is similar to that of TVOD. Moreover, the nPVR service may be independent of the EPG. When the user is watching a live program, the user may choose to record the program anytime.
In the technical solution in the prior art, all the foregoing three services are provided by the VOD server.
To implement the TSTV service, the VOD server generally records a live channel with the time shifting capability cyclically according to a set time window. When the user performs time shifting, the live mode is changed to the VOD mode; upon completion of time shifting, the live mode resumes.
For TVOD services, the VOD server uses an independent file for recording the programs. Upon expiry of the file, the contents are deleted directly.
For nPVR services, the VOD server records the programs independently to generate every media file according to the subscription request of the user, and the media files are managed by each user.
However, the prior art suffers from at least the following defects: The storage of the VOD service contents and the provision of the VOD service mode are both undertaken by the VOD server, and one service corresponds to a type of stored contents; consequently, the content management is decentralized and some contents are stored repeatedly. For example, if the CCTV1 channel is defined as a time-shifted channel, the VOD server may retain the files in a specific time segment of the channel as time-shifted recorded files; if the “News Broadcasting” program (which is broadcast from 19:00 to 19:30) on this channel supports TVOD, the program broadcast from 19:00 to 19:30 may also be saved as another file; finally, if a user uses News Broadcasting as an nPVR content, the system may record and retain another file for the user; therefore, in the worst circumstances, the same content corresponding to three services is stored repeatedly in three files. In a VOD service, the expense of storage accounts for a high proportion. However, the prior art is unable to manage or utilize storage properly.